Field of the Invention and Prior Art Statement
The present invention relates to an information reproducing apparatus which is capable of reproducing information quickly even when dust sticks to the apparatus.
In recent years, the amount of information processed by a computer or the like has increased, therefore, an optical information recording/reproducing apparatus which is capable of recording and/or reproducing information with high density using a light beam has been given attention.
In such an information recording and/or reproducing apparatus, as known by Japanese Patent Laid Open No. 2-21054/1990, the number of tracks on which a beam spot crosses and the crossing direction were detected from a reproducing signal and a tracking servo signal obtained by irradiating the beam spot on an information recording medium for reproducing information recorded on a track and other beam spots for obtaining the tracking servo signal.
Recently, several kinds of portable type large capacity memory, such as a so-called optical card on which an optical recording medium is added and a pocket notebook in which an optical recording medium is added has been developed. With the development, an information recording and/or reproducing apparatus has been also developed.
When the optical recording and/or reproducing medium is used as a portable type large capacity memory, it is not avoidable that the medium is stuck by dust or scratched while it is carried.
If there is dust or a scratch, the reflection of a beam spot is disturbed, so that the quantity of light entering a light detector which receives reflected light from a light recording medium has been different from a normal condition. Therefore, it is difficult to detect an accurate number of crossing tracks and the crossing direction. For example, we are apt to make a counting error of a crossing track number. Thereby, in an accessing method in which a beam spot is moved to an objective track based on the crossing track number and crossing direction, it takes a long time to gain access to an objective track to be reproduced. As a result, it has been difficult to reproduce recorded information quickly.